4513 datasheet(141/210 Pages) RENESAS

tên linh kiện	4513

Giải thích chi tiết về linh kiện	4-BIT SINGLE-CHIP MICROCOMPUTER

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APPLICATION

2.3 Timers

2-38

4513/4514 Group User’s Manual

Fig. 2.3.9 Watchdog timer setting example

g0 h

•

••

•

Activate Watchdog Timer

Watchdog timer is activated.

Watchdog timer enable flag WEF “1”

Watchdog timer enable flag WEF set

(WRST instruction)

Main routine (every 20 ms)

Reset Flag WDF

Watchdog timer flag WDF1 is reset.

“0”

Watchdog timer flag WDF1 cleared

(WRST instruction)

Main routine execution

Repeat

Do not clear watchdog timer WDF flag in interrupt service routine.

Interrupt may be executed even if program run-away occurs.

When going to RAM back-up mode

WRST

; WDF flag cleared

EPOF

; POF instruction enabled

POF

↓

Oscillation stop (RAM back-up mode)

In the RAM back-up mode, WEF, WDF1 and WDF2 flags are initialized. However, when WDF2 flag is set to “1”, at the

same time, system enters RAM back-up mode, microcomputer may be reset. When watchdog timer and RAM back-up

mode are used, execute the WRST instruction before system enters the RAM back-up mode to initialize WDF flag.

“!”: it can be “0” or “1.”

4513 bảng dữ liệu(PDF) 141 Page - Renesas Technology Corp